Abstract
Our day-to-day experience suggests that, with repeated exposure, we can easily acquire information about our environment. However, it is not clear how much exposure is needed for information to be useful for task performance. In a previous study we found that searching for different targets in the same set of 72 items did not facilitate search for other items within the same set. In this study we analyzed whether this was still the case when all targets shared one feature (color). In each trial a target letter was presented at fixation, followed by the search display. The search display was made of 72 colored letters (12 letters x 6 colors) and was the same for all searches (repeated visual search). Twelve different orange letters were used as targets. Location was constant for each target, but targets differed in eccentricity. Each target was searched for 6 times. We compared the results of two groups of participants. For the first group all 12 letters were targets in each block of trials. For the second group one of the letters, ‘W’, became a target only in the last two blocks of trials. Our goal was to determine if previous fixations on this letter while searching for other letters facilitated search. Results showed that RT decreased significantly with target repetition for all letters. Critically, when we compared RTs for the first search of the letter ‘W’ we found that RTs were similar. This was the case even though the second group of participants had performed 55 trials before searching for the W and had made, on average, 8 fixations on that letter during those trials. This suggests that just fixating an element when it is not a target is not enough to produce a memory trace. Facilitation requires repeatedly searching for the same item.